Discoverers Navigating
1564 - 1642
Mathematics is God's Language
zeitgeist | what is modern? | worldview | Influence | Background | Trial | Brecht | lesson
Precession of the equinoxes
A scientific problem of complex movement
The slow westward movement of the equinoctial points along the plane of the ecliptic by a rate of 50.27 seconds of arc per year resulting from a slow westward shift of the Earth's axis of rotation.
If the Sun is moving to the east, does that mean the moon moves to the west?
Overview:
Galileo: The person & the myth
1300 - 1633 - 1900
a sense of identity, symbolism, measuring reality
"these are the days of miracle & wonder"
Middle Ages
A sense of place: personal, social, native, & cosmic
Methodology:
Holton's Three criteria for science
Analytical
History of ideas vs. Biography
Primary vs. Secondary sources
The rationalization of Humanism -- Science & Art
Foundations of Modernity:
Galileo - Descartes - Hobbes - Newton - Locke
Newton referred to the world he created with calculus, gravity and telescopes as "modernity," because it replaced earlier alchemical, algebraic and Aristotelian worlds.
Galileo's times:
zeitgeist.
Age of Discovery
from the Council of Trent, 1560s
to the
English Revolution, 1640s; there ensued a challenge to authority.
The personality of and influences on Galileo;
Father was a music teacher, 1 of 7 children
Conflicts sacred & secular; thinkers & doers
Writings Sidereus Nuncius (1610) & Dialogo (1630)
Trial by the Roman Inquisition & faithful Christian Doctrine
Legacy of Galileo -- Freedom of inquiry -- Kepler's Laws
Scientific Revolution -- mechanism, utility, efficiency
Eventful moments in the Scientific Revolution
(internal history)
1477 earliest reprinting of Ptolemy's Geography
1492 First voyage of Columbus
1503 Vespucci's Novus Mundi
1509 Erasmus, In Praise of Folly
1513 landing in Florida of Ponce de Leon
1517 Reformation
1545-63 Council of Trent
1577 Tycho Brahe's discourse on comets
1590 microscope
1608 telescope
1609 Kepler's Astronomia Nova
1620 New Amsterdam fded.; Bacon's, Novum Organum
1634 Thomas Hobbes met Galileo Galilei
1649 Beheading of Charles I of Great Britain
1687 Isaac Newton's Principia Mathematica
International history
(external events)
1558 Fall of Calais from England to France
1560 Tycho Brahe begins observations of an eclipse
1561 Fallopius published his Observations on Anatomy
1562 Akbar the Mogul Emperor of India
1563 Cathedral built in Mexico City
1566 Netherland's revolts against Spain & the Inquisition
1569 Mercator's Projection of the map of the world
1572 Catherine de' Medici assists in Protestant massacre
1578 Sir Francis Drake in California
1582 Hakluyt's Voyages published about the world
1587 Beheading of Mary, Queen of Scots
1593 Portuguese & Dutch colonize Africa
1602 Dutch East India Co. established
1607 Jamestown, Virginia founded
1628 New Amsterdam (York) founded by the Dutch
1648 Treaty of Peace of Westphalia ends the 30 years war
1680s Locke assists in the founding of the Carolina colony
1688 "Glorious Revolution" William & Mary's reign
Natural Philosophy was set against empirical philosophy
1500 - 1600
Aristotle "the Master of those who know" said Dante (8)
the most profound characteristic of nature is change (process)
Euclid's Elements, Book V theory of proportionality was the most
read book of the ancient world (Greaco-Roman period of 1st century through
the medeivel period of the 15th century).
|
1. |
techne | the Greek idiom for practical knowledge | experience |
|
2. |
episteme | the Greek idiom for scientific knowledge | reason |
Their sources & goals were very different; predictionof events vs.
fundamental causes of conditions in which events occurred.
During the 16-17-18 centuries -- Scientific Revolution -- the search for laws replaced the preoccupation with causes (11). Such was Galileo's law of falling bodies -- there is a sureness & a necessity in the displays of Nature
Universities were conservative resisted the new knowledge from the field of mechanics, craftsmen, military -- civil & hydraulic engineers (16)
Even the church had asked Copernicus to solve a problem raised by the failure of existing calendars to accurately predict Easter!
Galileo was a craftsman, a measurer, and an experimenter who unlike Bacon & Descartes offered no overall philosophy of science. Instead he wedded theory & practice to predict the logical consequences of his observations. (2-20)
Galileo's fundamental difference from his detractors
was
"an epistemological conviction about reliable knowledge." (37)
"Measurement belongs to science; eternal truth belongs to faith, whether philosophical or theological."
actual measurements of the speed (velocity = v) of free fall confronted Galileo with problems that natural philosophers had avoided. "rigorous quantitative analysis of continuous change"
"God speaks in the language of mathematics." Galileo is told to have said.
Galileo's
Early influences, family:
Mother's work & piety {faith, practicality, devotion}
His Father's music {meter, measurement, order}
Galileo's intellectual antecedents:
Euclid's Elements most widely read book of antiquity
Archimedes -- measurment & predictable laws of behavior
Aristarchus -- measurement & heliocentric cosmos
Copernicus -- corrected the error in measurement - heliocentric
Kepler (1598 saw his work) combined observation & math.1583, Galileo -- outside of the University first read Elements
1586 he investigated hydrostatic balance based on Archimedes
great influence of a practical sort & mathematics in music from his father Vincenzio {mathematical law based on string length}1587 his notoreity led to a freindship with C. Clavius who taught astronomy in the Jesuit College in Rome
1589 Chair of Mathematics at University of Pisa (3 yr. appt.)
1592 University of Padua (VENICE) Professor of Math.
tensions with Rome, expulsion of the Jesuits, &
1600 the burning of Giordano Bruno by the Inquisition
Galileo's academic experiences:
pendulum experiment 1602
craftsmanship -- ocular scope
experiment -- hydrostatics & motion
design for a harbor at Livorno
observation of the heavens: moon, Jupiter, Saturn, Venus.
Fra Paolo Sarpi befriended Galileo - lifelong intellectual freindship Galileo wrote Sarpi initially about acceleration (1604) 1609 the telescope.
For Galileo, military necessity dictated many practical inquiries into surveying, fortifications, harbors, & mechanics!
1595 Galileo used Copernicus for the first time formally to describe his equations about the tides -- practical investigation
1602 pendulum experiment -- he became good at setting
them up
1603 motions & velocity of falling balls on an inclined plane.
"distances from the rest are as the squares of the
elapsed times." (33) careful measurement -- frequent errors but a
willingness to correct those errors.
Three Movements collided during his lifetime:
Reformation
Giordano Bruno burnt by the Inquisition in 1600 as a heretic
Kepler a German Lutheran proved Copernicus correctAristotelians
division of ethereal and earthly matter; the heavens as sublime & in motion, versus the earth as base matter at rest.
Ptolemaic, geocentric universeAuthority of the high clergy
factions: Jesuits versus Dominicans
Roman inquisition (est. 1542), the Index of prohibited books (est. 1571), & strict rules for heresy trials adopted in 1588.
In rejecting the geocentric or Ptolemaic model of the heavens, Galileo proposed that the Copernican model based on the heliocentric conception of the solar system was the correct way to interpret the behavior of planets, moons, comets and the Earth's position in the solar system.
Sidereus Nuncius, (1610) views of the Moon, sunspots, Jupiter's "Medicean Stars", the phases of Venus, experimental philosophy
"Again, it is a most beautiful and delightful sight to behold the body of the Moon . . ."
"I have discovered four planets, neither known nor observed by any one of the astronomers before my time, which have orbits round a certain bright star, one of those previously known, like Venus & Mercury round the Sun, and are sometimes in front of it, sometimes behind it, though they never depart from it beyond certain limits."
"Now let me review the observations made by me . . . inviting the attention of all who are eager for true philosophy. . . ."
"just as the shadows in the hollows of the Earth diminish in size as the Sun rises higher, so also the spots on the Moon lose their blackness as the illuminated part grows larger and larger."
"The grandeur of such prominences and depressions in the Moon seems to surpass both in magnitude and extent the ruggedness of the Earth's surface. . . ."
El Dialogo
"The First Day"
The character and effectiveness of those laws of nature
Philosophical foundations of the "new astronomy"
two theories as to the substance of heavenly bodies
invention of writing
9 Copernicus 10 Aristotle 11 Plato 12 Geometry
14 Aristotle's divisions of the universe "the Celestial & the
Elemental"
32 "Sensible experience must be preferred to human reason."
33 helio vs. geocentricity
56 telescope
72 proof of the moons rough surface
"The Second Day"
physical arguments are inconclusive on the diurnal motion of the earth
about its axis & around the sun
Peripatetics vs. Alexandrians {ancient centers of Greek science}
observation & telescope
inertia
laws of falling bodies
centrifugal force
pendulum
analytic geometry
112 - 120
to 151
"The Third Day"
letting the conclusion influence your view of the data and affecting
your presentation of adequate evidence
276 - 278
daily rotation and annual revolution of the earth
proof: due to moving sunspots
circle as perfect motion (Platonic & Ptolemaic)
stars as observable evidence for the earth's rotation
377-400
Tides in the Adriatic & Atlantic require the motion of the earth, 416-
Galileo's
Dialogue on Two Great World Systems
[1632]
"Several years ago there was published in Rome a salutary edict which, in order to obviate the dangerous tendencies of our present age, imposed a seasonable silence upon the Pythagorean opinion that the earth moves."
"its origin . . . in passion none too well informed."
"clip the wings of reflective intellects by means
of rash prohibitions." {p-1}
"a witness of the sober truth."
"I have taken the Copernican side in the discourse." {5}
"they are content to adore the shadows, philosophizing not with due circumspection but merely from having memorized a few ill-understood principles." {6}
Written to commemorate two Italian intellectuals:
Giovanni Francesco Sagredo Venetian
Filippo Salviati Florentine
"May it please those two great souls, ever venerable to my heart,
to accept this public monument of my undying love."
Trial of Galileo April 12, to June 21, 1633
Files of his trial include information on Galileo from 1611
1616 Holy Inquisition had banned the profession of belief in Copernicus
as heretical
1632 Pope Urban VIII wrote: "Your Galileo has ventured to meddle
with things that he ought not to and with the most important and dangerous
subjects which can be stirred up these days,"
Trial presided over by Ten judges; all Cardinals of the
Dominican Order
neither charges nor evidence was shared with the accused
written documents need not be produced
"I abjure, curse & detest the aforesaid errors and heresies,
and generally every other error & sect whatsoever contrary to the
said Holy Church,"
G. Galilei, 22 June 1633
El Dialogo
THREE PRINCIPLE HEADINGS:
1) experiments on earth are insufficient to conclusively prove the earth's motion or rest.
2) celestial phenomena will be examined, strengthening the Copernican hypothesis.
3) propose an ingenious speculation about the motion of the tides and the earth's diurnal rotation.
"Brecht was all wrong about the seventeenth century in general and about Galileo Galilei in particular."
It is a paradox. The historical truth, rejected for its implausibility, has the air of an artifact, whereas the actual artifact, the play, has an air of truth."
Another paradox: only when a figure has become legendary is he or she a good subject for a history play."
Because the historical dramatist is concerned with the bits of history that have stuck in people's imagination, he may well find himself handling bits of pseudo-history that are the very products of people's imagination."
"After all, very much of our 'knowledge' of the past is based on fiction."
"So should we be prepared to see a modern, Marxist playwright distorting history in order to prepare young Communists for some future Battle of Russia?
. . . even for spectators who know that a history play is bad history, such a play might still seem to have some sort of special relevancy, a more urgent truth."
The present often intrudes upon the past:
The Church's canonization of Joan of Arc (1920s) after World War One!
"Like Saint Joan (GB Shaw) and all other good history plays, Galileo
is about the playwrights own time.
"There are two Galileo plays here, both exist in their entirety, the version of 1938, and the version of 1947."
"He [Brecht] was a poet, but a poet in love with the idea of science, a poet who believed that his own philosophy was scientific:"
Brecht's words:
1930s
"Take care when you travel through Germany with the truth under your
coat!"
1940s "The atomic age made its debut at Hiroshima in the middle of
our work. Overnight the biography of the founder of the new system of
physics read differently."
"In this respect, Galileo I is a 'liberal' defense of freedom against tyranny, while Galileo II is a Marxist defense of a social conception of science against the 'liberal' view that truth is an end in itself." {18-19}
Is Galileo or "the people" the real hero? {33-34}
"Galileo, according to Brecht, was one who at a crucial moment was
disloyal to his 'side' in the 'the fight.' That can hardly be unimportant.
The character will stand, as Brecht intended, as an exemplar of a certain
kind of weakness. But will it not stand, even more impressively, as the
exemplar of human greatness, a proof that greatness is possible to humankind?
For that matter would the weakness be even interesting if it were not
that of a great (which is to say: in many ways, a strong) man?" {41-42}
"The Science Fiction of Bertolt Brecht" by Eric Bentley, Drama critic
Brecht's attributions to Galileo the legend -- universal qualities:
1 truth or many truths
power or pluralism
ethics or moral certainly
special circumstances:
vernacular (Italian) challenge to authority [Latin]
anomalies in the heavens; comets, Medicean moons, Venus
wars of the Reformation (1517-1648)
empirical evidence for heliocentricity, precession of the equinox
Galileo's significance:
Assault on Aristotelian doctrines
NeoPlatonism & new mathematics
Conservation of motion
Copernican
observational & experimental method
mathematical proof
practical crafts people
useful science
inventive viewpoint
modern worldview
mechanism
atomism
mercantilism
According to Gerald Holton an historian at Harvard any description in order to be scientific must be refutable and be consistent across three different perspectives or have integrity:
1. THEORETICAL or rational -- see Gell-Mann and Einstein
2. EMPIRICAL or experience -- see Newton and Darwin
3. HEURISTIC or discoverable -- see Feynman and Watson
Ancient cosmology stressed: Cosmos was alive; made up of Four elements (earth, air, fire, water) ; earth was the center of the heavens and made of base matter; celestial realm was dwelling place of perfect forms, this world was a reflection of the celestial quintessence; humans were part of a "SCALA NATURA" (a chain of being) and were divinely made (as were all things) of four material humors and an immortal soul. Two oppositional forces called gravity and levity account for the movement of the heavens and the disc-like earth.
A refutable theory
Copernican vs. Ptolemaic world
systems
Superior relation of theory to empirical observation:
Eclipses - earliest recorded eclipse is 19 March 721 BC
- 29.5 days = 1 lunation of moon about the earth
- 19 year cycle = 235 lunations
• Precession of the equinoxes, due to the instability of earth's rotational axis
• periodicity in the Earth's axis of rotation occurs over a 25,900 year cycle
On the Julian calendar by 1425 the vernal equinox fell earlier and earlier than March 21
by 1570, the equinox was falling 10 days before 21 March. The October 1582 calendar was calculated on the basis of the Copernican model of the cosmos.
Hipparchus in 127 BC recognized that the equinoxes move with respect to the fixed stars and this is called a:
"precession of the equinoxes"
Modern conceptions of the universe suggest that inanimate matter --in the form of 92 natural elements make up the cosmos; that humans like all life have evolved using 26 of those elements. Four basic forces account for the movement of quarks, atoms, molecules, and galaxies in a hierarchy of material forms with the sun as a small star in an arm of the Milky Way galaxy of stars.
Comments on the scientific method.
